Achyranthes bidentate saponins protect rat articular chondrocytes against interleukin‐1β‐induced inflammation and apoptosis in vitro

Achyranthes bidentate Blume (Niuxi) is often employed for treatment of arthritis in Traditional Chinese Medicine and possesses anti‐inflammatory properties. Phytochemical and pharmacological studies proved the oleanane‐type saponins to be the main bioactive principles. In the present study, protective effects of A. bidentata saponins (ABS) on inflammation and apoptosis in interleukine‐1β (IL‐1β)‐induced chondrocytes were investigated. Rat chondrocytes were pretreated with ABS at 3 μg/mL, 10 μg/mL, and 30 μg/mL, and subsequently stimulated with IL‐1β (10 ng/mL). Methylthiazolyldiphenyl‐tetrazolium bromide assay and annexin V/propidium iodide dual staining demonstrated that ABS could protect IL‐1β‐induced chondrocyte injury. ABS suppressed IL‐1β‐induced apoptosis by suppressing the activation of caspase‐3, inhibiting levels of proapoptotic proteins Bax and Bad, decreasing p53 protein phosphorylation, and promoting the expression of antiapoptotic protein Bcl‐xL and proliferating cell nuclear antigen. IL‐1β‐induced inflammation and matrix degradation were also alleviated by ABS through the downregulation of the expressions of matrix metalloproteinases 3 and 9 and cyclooxygenase‐2. Moreover, ABS inhibited IL‐1β‐induced nuclear factor κB activation in rat chondrocytes. We demonstrated, for the first time, the protective effects of ABS on IL‐1β‐stimulated chondrocytes and their molecular mechanisms. Thus, it is suggested that ABS might be a potential drug in the treatment of osteoarthritis.